The fact that non-stop flight times are getting longer requires that passengers be provided with the maximum comfort by being offered the possibility of working, relaxing or even resting. This is the main reason why first-class seats or business-class seats are equipped with electromechanical actuators, such as motors, making it possible to obtain every position from that of an armchair to that of a bed. This is also why the passenger today has at his disposal a video screen, a telephone, a reading light and increasing numbers of information technology tools.
A control unit is used to control the screen and the other elements of the seat, such as the actuators or the reading light, which are capable of fulfilling a defined function. These seat elements, other than the screen, controlled by the control unit, are called nodes and generally form a network. The passenger can activate a node or the screen by means of a keyboard linked to the control unit.
In a traditional configuration, each position of a seat comprises a control unit in the form of a box. From this box emerge, in a star pattern, as many cables as there are nodes that have to be made to work and that have to be controlled. The fact that this control unit is situated beneath the seat gives rise to many cables which, with the box, take all the space available under this seat. These cables burden the structure of the seat and give rise to malfunctions.
In another configuration, a control unit common to several seats, and electronic modules offset in each node are connected to one another by means of a CAN type multiplexed node. The wiring of the seat is thereby considerably lightened. However, a group of several seats can happen to be deprived of node functions in the event of a malfunctioning in a central processing unit.
In another configuration, such as the one described in the patent application FR-2817810, each seat has a central processing unit connected to the nodes of the seat by means of a CAN type multiplexed electrical network. A system of this kind limits the risks of malfunctioning of a seat unit when a central processing unit is defective. However, the number of cables under the seat remains great.